This invention is in the general field of construction and relates to windows and doors. The invention especially relates to a glass spacer for insulated, dual pane windows or multi-glazed windows.
The present invention particularly provides an improved insulated glass spacer which is adapted to be used with plastic film positioned between two panes of glass in an insulated glass.
It is generally recognized that doors and windows on exterior walls allow major heat losses far in excess of their relative cross-sectional areas. A variety of solutions have been proposed or used to reduce this heat loss, including storm windows, plastic film over the glass panels, interior and exterior shades over the windows, and insulated glass or multi-pane windows. The latter are often preferred, but are more difficult to manufacture, relatively expensive and generally suitable only for new construction.
In manufacturing an insulated glass window, it is necessary that each pane of glass in the window be separated from the other by some type of spacer. These spacers are generally longitudinal plastic or extruded metal, rectangular or other desired shape, tubular members. A spacer which has found some degree of commercial success is a roll formed tubular aluminum member, rectangular in cross-section.
With soaring utility costs, a need exists for more thermally efficient window assemblies. More recently triple glazed windows have been grown in popularity.
In a triple glazed window, three panes of glass are separated by two spacers. Such construction is considerably expensive.
Various means have been proposed to reduce the cost of triple glazing or tripled-pane insulated glass. One type of window assembly utilizes a thin polyester transparent film, sometimes referred to as a "heat mirror" which is positioned or permanently installed between two panes of glass. The film is mounted or glazed in a plastic frame which is then glued or otherwise anchored to a regular or modified insulated glass spacer positioned between two panes of glass. In this case, the two glass panes are spaced apart a greater distance than they would be in normal double-paned or dual glazed insulated glass. The transparent film takes the place of a center glass panel and provides an effective "triple-glazed" window. For example, the U-value for a conventional double glazed window is 0.50 and about 0.31 for a triple glazed window. A double glazed window with a thin transparent polyester film dividing the air space has a U-value of about 0.22. Since such a window is transparent, it has a considerably improved appearance over solar control films which give windows a metallic or mirror like appearance.
It can readily be appreciated that the plastic film must be mounted between the glass panels in a taut position. It can also be appreciated that the means on which the film is mounted should reduce the visible window area as little as possible, and should be more or less invisible when viewed from within or without.
One means for attaching a plastic film to a frame and to hold it in a taut position is illustrated by U.S. Pat. No. 4,189,880 issued to Bollin on Feb. 26, 1980.
The patentee has provided a channel member for receiving an edge of a film sheet. The channel member has a central projection for receiving a groove on a T-shaped spline which is so constructed as to tightly fit in the channel member. The film is then stretched tautly and another edge locked in place, such sheet-engaging members are not particularly suited for holding a thin plastic sheet between two panes of glass.
More recently, U.S. Pat. No. 4,182,088 issued to Ball on Jan. 8, 1980 utilizes a clip-type channel member for receiving sheet material and using a rod to lock the sheet material in place in the channel opening. In cross-section, the channel member is shaped like a shepherd's crook.